kottke.org posts about Sam Arbesman

Ran across one of my favorite little pieces of writing the other day: Sixty Men from Ur by Mark Sumner. It's about how short recorded human history really is. The piece starts out by asking you to imagine if you view the history of life as the Empire State Building, all of human history is a dime on top.

Arthur M. Schlesinger, Jr., one the United States' great historians, is less than two lifetimes removed from a world where the United States did not exist. Through Mr. Schlesinger, you're no more than three away yourself. That's how short the history of our nation really is.

Not impressed? It's only two more life spans to William Shakespeare. Two more beyond that, and the only Europeans to see America are those who sailed from Greenland. You're ten lifetimes from the occupation of Damietta during the fifth crusade. Twenty from the founding of Great Zimbabwe and the Visigoth sack of Rome. Make it forty, and Theseus, king of Athens, is held captive on Crete by King Minos, the Olmecs are building the first cities in Mexico, and the New Kingdom collapses in Egypt.

Sixty life times ago, a man named Abram left Ur of the Chaldees and took his family into Canaan. Abram is claimed as the founder of three great religions. A few lifetimes before that, and you've come out the bottom of that dime. You're that close to it.

I was recently listening to a lecture by Kevin Kelly where he introduces the concept of touch generations, the idea of a list of people based on when one person died and when the next was born: one person is in the next touch generation of someone else if they were born when the other person died. So Galileo and Newton, while unrelated, are in successive touch generations because Newton was born the year that Galileo died. Essentially, it's a way of connecting lifetimes across the years.

Facts change all the time. The age at which women should get a mammogram has increased. Smoking has gone from doctor recommended to deadly while the healthiness of carbs and fat seems to be in constant flux. We used to think the Earth was the center of the universe, that Pluto was a planet, and that the brontosaurus was a real dinosaur. What we know about the world is constantly changing.

Samuel Arbesman is an expert in scientometrics, literally the science of science-how we know what we know. It turns out that knowledge in most fields evolves in systematic and predictable ways, and understanding that evolution can be enormously powerful. For instance, knowing how different branches of medicine overturn their bodies of knowledge can improve the way we train (and retrain) physicians.

The Half-Life of Facts features fascinating examples from fields as diverse as technology and literature. It will help us find new ways to measure the world while accepting the limits of how much we can know with certainty.

While fun to chronicle such similarities, these similarities can also be exploited in the same way. Mutational differences between DNA sequences can be used to understand the evolutionary history of a population, or even a group of species. And so too with variants of the same manuscript. A famous example of this is from a 1998 research article in the journal Nature that quantitatively studied the differences between the 80 surviving versions of Geoffrey Chaucer's The Canterbury Tales. By subjecting the variants to a battery of genetic analyses, the researchers were able to better understand the contents of the ancestral version, Chaucer's own copy!

As near as I can tell, if you grow up in the magical world (as opposed to be Muggle-born, for example), you do not go to school at all until the age of eleven. In fact, it's entirely unclear to me how the children of the wizarding world learn to read and write. There is a reason Hermione seems much more intelligent than Ron Weasley. It's because Ron is very likely completely uneducated.

My take is that wizards are jocks, not nerds; Hogwarts is not so much a secondary school as a sports academy. What's odd about that is that quidditch is an extracurricular...

The paper reports the discovery of two new planets around the nearby red dwarf star Gliese 581. This brings the total number of known planets around this star to six, the most yet discovered in a planetary system other than our own solar system. Like our solar system, the planets around Gliese 581 have nearly circular orbits.

The most interesting of the two new planets is Gliese 581g, with a mass three to four times that of the Earth and an orbital period of just under 37 days. Its mass indicates that it is probably a rocky planet with a definite surface and that it has enough gravity to hold on to an atmosphere, according to Vogt.

Gliese 581, located 20 light years away from Earth in the constellation Libra, has a somewhat checkered history of habitable-planet claims. Two previously detected planets in the system lie at the edges of the habitable zone, one on the hot side (planet c) and one on the cold side (planet d). While some astronomers still think planet d may be habitable if it has a thick atmosphere with a strong greenhouse effect to warm it up, others are skeptical. The newly discovered planet g, however, lies right in the middle of the habitable zone.

Sam Arbesman's prediction of May 2011 might have been too conservative. And 20 light years...that means we could send a signal there, and if someone of sufficient technological capability is there and listening, we could hear something back within our lifetime. Contact! (thx, jimray)

Of course, it's a bit more complicated than that, but here's an overview of what we did. Using the properties of previously discovered exoplanets, we developed a simple metric of habitability for each planet that uses its mass and temperature to rate it on a scale of 0 to 1, where 1 is Earth-like, and 0 is so very not Earth-like. Plotting these values over time and taking the upper envelope yields a nice march towards habitability.

The authors don't address this directly in their paper, but I wondered what the Moore's Law for planetary discovery might be -- e.g. every X years (or months?), the habitability of the most habitable planet discovered doubles. So I emailed Sam Arbesman and he said that his quick back of the envelope calculation would be "half a month or so"...which is an astounding pace.

There's a category of information that slowly changes throughout the course of a lifetime. Sam Arbesman calls them mesofacts.

These are facts which we tend to view as fixed, but which shift over the course of a lifetime. For example: What is Earth's population? I remember learning 6 billion, and some of you might even have learned 5 billion. Well, it turns out it's about 6.8 billion. [...] If, as a baby boomer, you learned high school chemistry in 1970, and then, as we all are apt to do, did not take care to brush up on your chemistry periodically, you would not realize that there are 12 new elements in the Periodic Table. Over a tenth of the elements have been discovered since you graduated high school!

How does it work? First, you draft your countries. There are about 200 countries in the world, so in a league of 10 players, each player chooses 15 countries. To keep things fair, there are distribution requirements: There must be at least two countries from each of North America, Europe, Asia, and Africa, and at least one country from each of South America and Oceania. This will prevent a team from loading up on certain areas of the planet. (Another option is to include a GDP cap.)

If you and someone else hate the same third person, but like each other, balance theory says you're golden -- all three can persist without changing their opinions. On the other hand, if all three of you despise the others, it's an unstable triad, as well as a wildly common plot point for crime movies. While there are numerous resolutions -- one person changes his preference toward another, a relationship tie is cut -- another route back to stability, albeit a messy one, is the gunning down of at least one person.

Arbesman has some videos and stills on his web site from the movies mentioned in the article as well as the relevant mathematical materials.

The possibility of a sudden time-in would loom large in every coach's mind at the most tense points in the game, introducing just enough concern and uncertainty to make the game different. Timeworn clock-management strategies would no longer be a given. And yet, for the average viewer on a Sunday, the game on the field would still be your father's football.